.chess{
  border: 1px solid lightgray;
  cursor: pointer;
  box-sizing: border-box;
}
.chess .chess-item{
  width: 40px;
  height: 40px;
  border-radius: 50%;
  box-shadow: 0 0 5px 1px gray;
  margin: 5px auto;
  display: none;
}
.chess .red{
  background: radial-gradient(#fff, rgba(255,0,0,0.52));
  display: block;
}
.chess .blue{
  background: radial-gradient(#fff, rgba(0,0,255,0.52));
  display: block;
}